115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

ATS622LSB

TRUE ZERO-SPEED,

GEAR-TOOTH SENSOR

6

DEVICE DESCRIPTION

Module description. The ATS622LSB true zero-speed

gear-tooth sensor system is a Hall IC plus magnet configu-

ration that is fully optimized to provide digital detection of

gear-tooth* edges in a small package size. The sensor is

packaged in a miniature plastic housing that has been

optimized for size, ease of assembly, and

manufacturability. High operating-temperature materials

are used in all aspects of construction.

The use of the sensor is simple. After correct power is

applied to the component, it is capable of instantly provid-

ing digital information that is representative of the profile

of a rotating gear. No additional optimization or process-

ing circuitry is required. This ease of use should reduce

design time and incremental assembly costs for most

applications.

Sensing technology. The gear-tooth sensor module

contains a single-chip differential Hall-effect sensor IC, a

samarium-cobalt magnet, and a flat ferrous pole piece.

The Hall IC consists of two Hall elements spaced 2.2 mm

apart, located so as to measure the magnetic gradient

created by the passing of a ferrous object (a gear tooth).

The two elements measure the field gradient and convert it

to a voltage that is then processed to provide a digital

output signal.

Magnetic signal before gain control

Magnetic signal after gain control

* In application, the terms “gear” and “target” are often inter-

changed. However, “gear” is preferred when motion is trans-

ferred.

-1000

RELATIVE TARGET POSITION

Dwg. GH-061-2

-800

-600

-400

-200

0

200

400

600

800

1000

AG = 2.75 mm

0.25 mm INTERVALS

AG = 0.25 mm

-1000

RELATIVE TARGET POSITION

Dwg. GH-061-3

-800

-600

-400

-200

0

200

400

600

800

1000

AG = 2.75 mm

AG = 0.25 mm

Dwg. MH-016-4

SENSOR

SOUTH

NORTH

PERMANENT

MAGNET

POLE PIECE

1

2

3

4

Internal electronics. The ATS622LSB is a self-

calibrating sensor that contains two Hall-effect elements, a

temperature-compensated amplifier, and offset cancella-

tion circuitry. Also contained in the device is a voltage

regulator to provide supply rejection over the operating

voltage range.

The self-calibrating circuitry is unique. After power up,

the device measures the peak-to-peak magnetic signal and

adjusts the gain using an on-chip D-to-A converter to

make the internal signal amplitude constant independent of

the installation air gap of the sensor. This feature allows

air-gap-independent operational characteristics.